All the OEM flywheels and flexplates found on LH 2.4 equipped cars are 60-2, meaning 60 tooths of which 2 are missing. This flywheel is a good choice for Megasquirt as it delivers high resolution timing, but it can be tricky to setup even if you read the MS manual several times.

Installing the flywheel:
The 2 missing tooths should be visible in the engine blocks starter hole when the engine is at TDC, if you get it wrong the missing tooths will be 45 degs off, and not visible at all through the starter hole. The Volvo Greenbooks have a different way of setting the correct orientation of the flywheel/flexplate, but this method is foolproof and easier to remember.

Crank at TDC, the 2 missing tooths pointing at the starter (click image to enlarge):Notes to image above: The 2 holes the arrows are pointing at are balancing holes and not the actually missing tooths, but they are located exactly there. When the flywheel/flexplate is viewed from the side the missing tooths are actually 2 missing holes! The numbers on the flywheel is only for megasquirt, they show the tooth number and its offset in degs from TDC.

Flywheel bolts:
The Volvo greenbook says you should always use new bolts, i have always reused the old ones and had no issues what so ever. But keep this in mind when judging whenever to ruse the bolts or not. The bolts should always be fixed with thread locking compound, you do not ever want the flywheel to break loose. According to the Greenbooks tightening torque for the bolts are: 70 Nm / 52 ft.lb, opposite bolts should be tightened together in a cross pattern. First tighten all bolts gently by hand, then tighten to specified torque. Looking at the 8 bolts counting clockwise the pattern is: tighten bolt #1, then #5, tighten #3, then #7, tighten #2, then #6, tighten #4, then #8.

If you just needed to install the flywheel/flexplate you can quit reading now, all the info below are for using 60-2 with Megasquirt.

Using the 60-2 flywheel with Megasquirt 1/2/3/extra
First you need to choose a tooth that will give a good trigger angle (usually between 50 and 90 degs BTDC). Look at the image above, the outer numbers are the tooth offset, tooth 0 is the first missing tooth, tooth 1 is the second missing tooth, tooth 2 is the first non missing tooth, and the first valid tooth that can be used to trigger on. The inner numbers are the offset in degs from TDC, on a 60-2 wheel there is 360 / 60 = 6 degs between each tooth. To stay in the 50 <-> 90 BTDC window valid tooths are tooth 2 to 8 both included.

Programming Megasquirt for 60-2 in Tunerstudio:

Wheel decoder settings:
First we need to tell Megasquirt what type of wheel we have, a 60-2 wheel have 60 base teeth (A), and 2 missing teeth (B).

Selecting a tooth for trigger A:
Trigger A is the trigger tooth for cylinder 1 and 4, i usually choose tooth 5 ('C') at 69 degs, as i like my trigger angle to be in between the limits, therefore the examples here will all use tooth 5 ('C').

Selecting a tooth for trigger B:
Trigger B is the trigger tooth for cylinder 2 and 3, on an even fire 4 cylinder engine this is the tooth exactly 180 degs from trigger A. In other words its "trigger A" tooth +30 tooths (60 tooths / 2), knowing this "trigger B" tooth must be 5 + 30 = tooth 35 (D).

Setting the trigger angle:
In "spark settings" set the "trigger angle" to the angle of the tooth chosen above (G). If your timing is slightly off (a few degs) adjust this value, if its more than a few degs off something else is wrong and you need to figure out what it is!

Trigger return:
Trigger return is used for calculating the timing while cranking the engine, the engine speed varies greatly while cranking, so using a tooth directly to fire the spark gives more accurate timing while starting the engine. If you dont want to use "trigger return" just put in 0's for both trigger A return (E) and trigger B return (F), and select "time based" in "cranking timing" (H)

Trigger A return:
Look at the flywheel image above and select a tooth that matches your desired cranking advance, OEM is usually around 12 degs BTDC. Using 12 degs as a reference, gives a choice between tooth 15 at 9 degs and tooth 14 at 15 degs, in this example tooth 15 (E) is used for 9 degs cranking advance.

My ignition options screen looks nothing like those, anyone interested in helping me get mine setup to semi match this as this data. The msq i have here already for another car matches this but none of the options screen match mine.

(02-26-2014 04:53 AM)Shifted Wrote: Also 'skip pulses' should be set to 2 instead of 3, amirite?

Skip pulses is the number of ignition events to ignore at cranking. Its
used to allow MS some time to calculate the correct advance before
firing a plug. Iirc its not important when using a 60-2 wheel because
after the missing tooth, MS starts to count teeth and therefore knows
where the engine is within 6 degrees of error.

might be a little bit before the question is answered by those in the thread, wolfie's last login was ~1yr. ago. are you still on the teebeezy? can probably get a quick answer over there from linuxman or if you try PM maybe they get an alert or something.